The goal of the proposed research is to evaluate the applicability of Coated Crystal Attenuated Total Internal Reflection (CC-ATR) Fourier Transform Infrared Spectroscopy for analyzing low molecular weight species in aqueous solutions. Preliminary experiments have indicated the CC-ATR technique provides increased sensitivity over IR analysis using uncoated ATR elements. It is envisioned that the role of the polymeric coating is to concentrate the analyte within the depth of penetration of the IR radiation within the medium adjacent to the ATR element.The increased concentration of analyte within this region results in increased sensitivity for detection of analytes of interest. The coatings to be investigated include: poly(vinylchloride) with varying levels of plasticizer added and five commonly used GC stationary phases: squalane (hexamethyltetracosane), Apiazon N, ( a hydrocarbon grease), Silicon OV-101 (100 percent methyl), Silicon OV-3 (10 percent Phenyl, 90 percent Methyl) and Silicon OV-25 (75 percent Phenyl, 25 percent methyl). The test analytes initially chosen will include: nitrobenzene, acetophenone, acetonitrile, toluene, carbon tetrachloride, caffeine, acetylsalicylic acid and acetaminophen. These analytes will provide data for a representative range of functionalities. The limits of detection for each solute and coating material will be determined using aqueous solutions under both equilibrium and non-equilibrium conditions. Additionally, the sensitivity versus time relationship will be determined for each analyte and polymeric phase. The potential for using CC-ATR for monitoring aqueous waste streams having low levels of organic contaminants will also be investigated. The CC-ATR technique has potential for greatly increasing the importance of FTIR as a bioanalytical method. It is expected that this work will also be directly applicable to the rapidly emerging technology of mid-IR transmitting fiber optics.